WSP06657

• File Number: 8210.120.90.B
• Description: 7 Basin States/10 Tribes
• Basin: Colorado Mainstem
• Date: 8/28/1991
• Author: State of California
• Title: Conceptual Approach for Reaching Basin States Agreement on Interim Operation of Colorado River System Reservoirs, California's Use of Colorado Riber Water Above its Basic Apportionment and Implementa
• Water Supply Pro - Doc Type: Publication

Water Bank or to resolving tbe long-term issues on the Colorado
River insofar as they do not adversely impact other states or other
contractors.

K. Colorado River System Reservoir Ooeration Studies
for 1992 Annual Operating Plan

The storage in the Colorado River System reservoirs is
projected to be 41.1 maf, 69 percent of capacity, on September 30,
1991. This amounts to 14.1 mat below that quantity ot vacant space
required on January 1, 1992 tor flood control by the U. S. Army
Corps of Engineers Flood Control Regulations for Lake Mead. The
factors and their influence on the drawdown from March 1988 through
December 1991 are displayed in Figure 1 and have resulted from the
following:

Bureau of Reclamation's Anticipatory Flood
Control Releases and Releases Pursuant to
U. S. Army Corps of Engineers Flood Control
Regulations (July 1987-February 1988)

MAF %

2.2

16

United States Deliveries to Mexico to satisfy
Mexican Water Treaty (March 1988-December 1991)

United states Obligation to Implement
Permanent and Definitive Solution to the
International Problem of the salinity of
the Colorado River (March 1988-December 1991)

6.0

43

0.5

:3

Regulatory Waste

Lower Division states' Use above 7.5 MAF
(January 1988-December 1991)

0.3

:::

0.2*

1*

Reservoir Evaporation and Below
Normal Runoff (March 1988-December 1991)

Total

4.9
IT:l

35

100

* This value would be less if unmeasured return flows
were credited to the Lower Division states.

Technical analyses of future reservoir system operation that
the Bureau of Reclamation has conducted to date with newly revised
Upper Basin depletion schedules for the 1992 Annual Operating Plan
show that water can be released to meet all requests for reasonable
beneficial consumptive use in the Lower Division states in 1992
while protecting the certainty of each Basin state's basic
apportionment. Based on the 85-year hydrologic record, all such
requests could be accommodated in 1992 without creating any risk of
shortages to any Colorado River mainstream water user over the next

11